Enhancements to virtualenv
Add a line like export WORKON_HOME=$HOME/.virtualenvs to your .bashrc.
Add a line like source /path/to/this/file/virtualenvwrapper_bashrc to your .bashrc.
Run: source ~/.bashrc
A list of environments, empty, is printed.
Run: mkvirtualenv temp
This time, the temp environment is included.
Run: workon temp
The virtual environment is activated.
For more details, refer to the column I wrote for the May 2008 issue of Python Magazine: virtualenvwrapper | And Now For Something Completely Different.